As it is well known, a MEMS device (micro-electro-mechanical system) is a micro device which integrated the mechanical and electrical functions in a silicon chip or die realized by using the lithographic techniques of micro manufacturing. The final assembled device is typically made of the silicon die wherein the MEMS is integrated and, optionally, of integrated circuits for specific applications mounted on a substrate, for example, of the LGA or BGA type (Land Grid Array or Ball Grid Array), flanked or piled onto the MEMS device, using the conventional assembling processes.
A cover or cap fixed to the substrate, encapsulates the MEMS device and the other integrated circuits mounted on the substrate, forming the package for protecting it from external physical stresses.
If the MEMS device is a pressure, gas or liquid sensor or a microphone, the cover is provided with holes for allowing the interaction between the device and outside of the assembled device.
It is also known that the substrate of the LGA/BGA type is formed by conductive layers insulated from each other by means of layers of insulating or dielectric material. The conductive layers are shaped in conductive tracks insulated from each other by layers of insulating or dielectric material. Conductive holes, called “vias”, are typically realized through the insulating layers with a vertical orientation with respect to the layers, to form conductive paths between conductive tracks belonging to different conductive layers.
The MEMS devices are then electrically connected to the outside of the final device, through wires which connect contact lands provided on the MEMS devices with the conductive tracks present on the substrate inside the cover.
Although advantageous under several aspects, these types of assembled electronic devices including MEMS sensors require, between the cap/cover and the substrate, a welding ring.
Moreover, the formation of this cover/cap which completes the assembled electronic device provides a series of process steps which are not provided in the realization of integrated circuits, with a considerable cost increase.
There is a need for electronic devices including MEMS devices and having such structural characteristics as to allow this electronic device to be made with manufacturing processes of conventional integrated circuits, overcoming the limits and/or the drawbacks still limiting the electronic devices realized according to the prior art.